By Roderick Floud
By James B. Beard
By Roger Balls
By John W. Mastalerz
By John E. Preece, Paul Read
By A. Faniran, O. Areola
By Ruck, H.C.
By Richard J. Chancellor
By G. R. Dixon
By F.S. Hardy, G.D. Watson
By James L. Brewster (Horticulture Research International, Wellesbourne, UK)
By Pete Brown
By Dennis S. Hill
By Agriculture, Fish.& Food, Min.of
By Ian G. Walls
By Jasper N. Joiner
By Noel Kingsbury, Andrea Jones
By Anne Starling, Peter Loosley, Tessa Lovatt Smith
By arthur j. simons
By Natural History Museum
By Paul Power